Feed water preheater



Dec-.27,1935 P SBENNETT 2,141,899

FEED WATER PREHEATER Filed June 16, 1957 i Inventor v Frank fermtt, b Ma iis AttoPneNLj.

Patented Dec. 27, 1938 UNETED STATES PATENT GFFiCE General Electric Com New York pany, a corporation oi application June 16, 1937, Serial No. 148,499

2 Claims.

The present invention relates to an improved heat exchanger particularly adapted for use as a `feed-water preheater in a high-pressure energy conversion system. It is an object of the invention to provide a preheater construction capable of withstanding the tremendous expansive stresses encountered in connection with a steam system operating at pressures of the order of one thousand pounds l0 per square inch. Other objects include the provision of a mechanically strong preheater which has suiiciently small weight and volume to favor its use in a steam locomotive or other propulsion vehiclel Where these factors are at a premium.

Particular features of the invention which contribute to the accomplishment of these results include the incorporation of several stages of preheating in a single casing, an improved casing structure and an improved connection and arrangement of the feed-water conduits within the casing. Other features will be apparent upon consideration of the following description taken in connection with the drawing in which the single figure is a sectional view of a preheater construction suitably embodying the invention.

The illustrated construction comprises an elongated casing including a plurality of separate sections adapted to receive heating fluid at various pressures and conduits running longitudinal- .30 ly of the casing for receiving feed-Water or a corresponding fluid to be heated. In the use contemplated, the conduits may be required to transmit water at a pressure as high as from 1500 to 2500 lbs. per square inch.

The casing comprises a pair of end sections I and vI I and one or more intermediate sections, of which only a .single section, numbered I2, is shown. The various sections are separated from one another by means of partitions I3 and I4 40 which are clamped between flanges IE and II attached to the casing sections and held in place by bolts I5 or other externally accessible removable :securng means. In connection with each section there is provided an escape duct I8 which may lead to acommon safety valve (not shown) operable in case of excessive and unpredictable pressures being generated within the casing.

The casing as a whole is provided at its extremities with rounded end Walls I9 and. 2i) which 50 are shown as being welded to the casing so as to impart a maximum of mechanical strength thereto. Relatively small openings provided in these end walls are closed by bulbous manifold headers 22 and 23, which thus form parts of the walls. As 55 shown the headers are secured in place by means ci lianges 25 and 25, which are welded to the headers and removably joined to the casing wall by means of externally accessible bolting connections. It will be seen that since the end sections of the casing are separably connected both 4-ii to the headers 22 and 23 and to the partitions I3 and I4, they may be removed in case of need by simply severing the external pipe connections and 4opening the bolted joints. Furthermore, after such removal the interiors of the various "l0 intermediate casing sections may be reached conveniently.

Due to their relatively small size and generally rounded or bulbous shape, the headers 22 and 23 are well adapted tostand very high pressures. l5 Correspondingly high strength is realized in connection with the feed-water conduction system by utilizing for this purpose a vplurality of small Vdiameter conduits 21, 28,*29 and 3S traversing all p of the casing sections and extending between 2D the manifold headers. In accordance with the invention, each conduit comprises one or more sinuously convoluted vor helical portions and, preferably, includes such a portion Within each of the casing sections. The inherent exibility .25 of such an arrangement permits the stresses created by the passage of high pressure fluid to be lequalized and in part relieved without danger of mechanical rupture. As a result, even with pressures on the order of 2500 pounds per square inch, 30 it is possible lto avoid the expense and complication of providing a separate expansion permitting device such as a manifold header movably mounted within the external casing.

According tothe indicated arrangement, the various feed-water conduits 2l, 28, 29 and 3B are arranged in parallel concentric convolutions. In order to assure uniform water heating and incidentally uniform expansion of the individual conduits, it is desirable to reverse the relative positions or'order of concentricity of the conduits at one or more points along the length of the casing and preferably in each casing section. This feature vis illustrated, for example, by the conduit arrangements shown respectively to the left and to the right of the partition I3. In this connection, it will be seen that the conduit 21 which assumes the innermost position in the casing section I 0 is brought to the outermost position in the casing section I2 and that the positions of 50 the remaining conduits are correspondingly reversed.

It will also be noted that thoseportions of the conduits which lie in one casing section are joined to those which lie in the next casing section by means of fused metal connections indicated at 3l and 32, respectively. The connections 3l are so placed that when the casing section I is taken oif, the connections may be severed and the partition I3 removed by sliding it to the left. Such removal is made possible by means of packing sleeves 33 which permit relative motion of the conduits and partition but prevent the leakage of steam between the casing sections. After the partition is lifted oif, the interior of the intermediate casing section is rendered accessible so that any necessary repairs can be made. If the remainder of the conduit connections are arranged in similar fashion, all of the casing sections can be opened in the same way with a minimum of mechanical difficulty.

In using my invention in connection with feed- Water preheating as, for example, in a high pressure steam locomotive system, the feed-water may be introduced into the manifold header 23 from the condenser of the circulating system. After fiowing through the casing, the heater water is withdrawn from the manifold header 22 from which it may be led into the high pressure boiler. In its passage through'the preheater, the feedwater is in counteriiow to heating fluid which may be supplied, for example, by extraction from the various stages of a steam turbine. Thus, steam at highvpressure, say 400 lbs., may be introduced into the casing section I 0 through an inlet connection 35. The water formed by condensation of this steam may be continuously removed by draining into a steam trap 36 which connects with the casing by a drainage duct 31 and a pressure equalizing connection 38. The steam trap may be of conventional construction and is adapted to permit passage of water without permitting escape of uncondensed steam from the casing section lll. The water removed through the trap is led into the intermediate casing section l2 through a duct 39 by which it is returned to the circulating system in such a manner as not to be required to flow over the conduit surfaces. By means of a second inlet pipe 40, steam at a pressure below that of the first casing section is introduced into the intermediate casing section I2 from which it is removed through another steam trap 42 in the manner already described. In this case, however, the end casing section 20, into which water from the trap 42 is led through a conduit 43, comprises a so-called drip cooler adapted to be entirely filled with liquid condensate. While the heat content of the liquid is low with respect tothat of the steam as introduced into the preceding casing sections, it is still high enough with respect to the incoming feed-water so that an appreciable increase in economy is realized by the disposition indicated. From this last heat exchange section the outgoing water is drawn through the steam trap 46 from which it may bereturned to the main condenser or if desired, to another portion of the circulating system.

The preheater construction described in the foregoing has been found to be particularly suited for use in connection with a steam locomotive in which the boiler pressure is in excess of 1500 pounds per square inch. This pressure can be handled with safety by the feed-water connections illustrated, while the preheater as a whole is characterized by a compactness and low Weight which makes it perfectly adaptable to the requirements of modern locomotive design.

While I have described the invention in terms of a particular structure, many modifications may be made without departure from the invention. I therefore aim in the appended claims to cover all such equivalent embodiments as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States, isz- 1. A preheater comprising an elongated multisection casing, partitions interposed between adjacent casing sections for effecting a iiuid tight separation thereof, a plurality of conduits traversing all the casing sections and having con-` centric helically formed portions within each casing section, the order of concentricity being reversed in adjacent sections, a bulbous inlet manifold extending through and forming a closure for one end of said casing for conducting fluid to be heated in said plurality of conduits, a bulbous outlet manifold extending through and forming a closure for the other endof said elongated casing for conducting heated fluid from said plurality of conduits, means for supplying heating elastic fluid at high temperature to said casing section at said outlet end, means for conducting heating elastic fluid at a lower temperature to an inter mediate casing section, means for conducting condensate from said outlet end section into said intermediate section, means for conducting condensate from said intermediate section to the inlet end section, such condensate comprising the heating fluid for said inlet end section and means for conducting condensate from said last mentioned section.

2. A preheater comprising an elongated multisection casing, partitions interposed between adjacent ca-sing sections for effecting a fluid tight separation thereof, a plurality of conduits traversingall of the casing sections, an inlet mani fold at one end of said casing for conducting uid to be heated in said plurality of conduits, an outlet manifold at the other end of said elongated casing for conducting heated fluid from said plurality `of conduits, means for supplying heating elastic fluid at high temperature to the casing section at the outlet end, means for conducting heating elastic fluid at a lower temperature to an intermediate casing section, means for conducting condensate from said casing Section at said outlet end into said intermediate section, means for conducting condensate from said intermediate section to the inlet end section, such condensate comprising the heatingi'luid for said inlet end section and means for conducting condensate from said last mentioned section.

FRANK S. BENNE'I'I. 

